Final answer:
The functional group that is capable ONLY of hydrophobic interactions is the hydrocarbon group, which is part of the aliphatic side chains of certain amino acids.
Step-by-step explanation:
The functional group that is capable ONLY of hydrophobic interactions is the hydrocarbon group, which is part of the aliphatic side chains of certain amino acids. Examples of amino acids with hydrophobic side chains include glycine, alanine, valine, leucine, isoleucine, and phenylalanine.
Hydrophobic interactions occur when the nonpolar hydrocarbon side chains cluster together, away from water molecules. This is because water molecules form hydrogen bonds with each other, creating a network of water molecules that exclude nonpolar molecules like hydrocarbons. By clustering together, the hydrocarbon side chains minimize their contact with water and maximize their interactions with each other.
These hydrophobic interactions play a crucial role in protein folding, as the hydrophobic side chains tend to bury themselves in the protein's core, away from water, while the hydrophilic side chains interact with the surrounding aqueous environment. By stabilizing the protein's folded structure, hydrophobic interactions contribute to the protein's stability and functionality.